Piston for a HPHT apparatus

ABSTRACT

A cartridge assembly for connection to the frame of a high pressure, high temperature press, comprising a front end. The front end may comprise a back up with a conical portion intermediate and coaxial with an anvil and a piston. The anvil may comprise a proximal end in contact with the back-up and a distal end being adapted to form part of a pressurized chamber within the frame. The back-up may comprise a truncated cylinder comprising a first and second interface that are joined by a peripheral cylindrical wall. The cylindrical wall may also comprise a portion extending normally from the periphery of the first interface to a net concave portion of the cylindrical wall. The net concave portion may extend from the normal portion of the cylindrical wall to the periphery of the second interface which abuts the anvil.

CROSS REFERENCE TO RELATED APPLICATIONS

In the Cross Reference to Related Applications, after “U.S. patentapplication Ser. No. 11/674,045 filed on Feb. 12, 2007”, now pending.

BACKGROUND OF THE INVENTION

The current apparatus relates to HPHT press apparatuses that are usedfor a variety of purposes including the production of super hardmaterials such as synthetic diamond. Typically, the manufacturing orsintering process for super hard materials in a HPHT multi-axis presscomprise of placing a payload inside a high-pressure, high-temperature,reaction cell. The reaction cell, made up of a pressure-transferringmedium is placed within the press's high-pressure chamber and subjectedto an ultra-high compressive force. During the press cycle, the pressureinside the cell must reach 35 kilobars, or more. Simultaneously, anelectrical current is passed through the cell's resistance heatingmechanism raising the temperature inside the cell to above 1000.degree.C. Once the super hard payload is subjected to sufficient pressure andtemperature for a prescribed period of time, the current is terminatedand the cell cooled. Pressure on the cell is then released, the anvilsretracted, and the cell with its super hard payload removed from thepress.

The amount of compressive forces a high pressure high temperature presscan exert on a given reaction cell and consequently the maximum reactioncell size and payload, are limited by the reaction forces the press canendure without catastrophic failure. Most often, the size and mass ofthe press determines its threshold capabilities for tonnage beforecatastrophic failure occurs. For example, the weight of a tie-bar presswith a tonnage rating of 3000 may exceed 60 tons. The weight of a4000-ton tie bar press may exceed 100 tons. Moreover, large tonnagepress types as described above are often expensive to construct and itsefficiency is typically proportional to the duration of its cycle andvolume of its payload.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention a cartridge assembly may be usedfor connection to the frame of a high pressure high temperature press,comprising a front end that may further comprise a back up intermediateand coaxial with an anvil and a piston.

In one aspect of the current invention the anvil may comprise a proximalend in contact with the back-up and a distal end may be adapted to formpart of a pressurized chamber within the frame of the press. The anvilmay comprise a cylindrical base connected to a tapered portion leadingto a working face of the anvil opposite the base. The tapered portionmay form a 35 to 55 degree angle with the cylindrical base while theworking face may comprise a first surface area which is substantiallyparallel with the base. The anvil may also comprise a chamfered regionwith a second surface area forming a 0.5 to 3.5 degree angle with thetapered portion and may be connected to the working face to form afrusto-pyramidal shape wherein the second surface area may comprise agreater surface area than the first surface area.

In another aspect of the current invention the back-up may comprise atruncated cylinder comprising a first and second interface that arejoined by a peripheral cylindrical wall. The cylindrical wall maycomprise a portion extending normally from the periphery of the firstinterface to a net concave portion of the cylindrical wall. The netconcave portion may extend from the normal portion of the cylindricalwall to the periphery of the second interface. The net concave portionof the backup may provide a means of effectively distributing loadstresses towards the cylindrical base of the anvil thus reducing theamount of shoulder loading frequently experienced in similar presseswhich may cause stress fractures and subsequently cause the press tofail. Specifically, the net concave portion may enable the backup toeffectively redirect and concentrate stress lines from the firstinterface, which may comprise a generally larger diameter, towards thesecond interface, such that the second interface comprises asignificantly stress matched interface, despite a smaller diameter, thatis able to distribute equal amounts of pressure across the cylindricalbase of the anvil.

In yet another aspect of the current invention a hydraulic system may beadapted to apply axial pressure to the backup through the piston whereina central portion of the piston may comprise an axial thicknessapproximately equal to the axial length of the backup.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram depicting an embodiment of a highpressure, high temperature multi axis press apparatus.

FIG. 2 is another perspective diagram depicting an embodiment of a highpressure, high temperature multi axis press apparatus.

FIG. 3 is a perspective diagram of an embodiment depicting the front andback end of a cartridge assembly.

FIG. 4 is another perspective diagram of an embodiment depicting thefront end of a cartridge assembly.

FIG. 5 is top perspective diagram of an embodiment depicting the frontend of a cartridge assembly.

FIG. 6 is a cross sectional diagram of an embodiment depicting acartridge assembly.

FIG. 7 is a cross sectional diagram of an embodiment of a piston.

FIG. 8 is another cross sectional diagram of an embodiment of a piston.

FIG. 9 is another cross sectional diagram of an embodiment of a piston.

FIG. 10 is another cross sectional diagram of an embodiment of a piston.

FIG. 11 is another cross sectional diagram of an embodiment of a piston.

FIG. 12 is another cross sectional diagram of an embodiment of a piston.

FIG. 13 is a cross sectional diagram depicting a prior art back-up.

FIG. 14 is another cross sectional diagram of the current inventiondepicting stress lines distributed through a backup.

FIG. 15 is a cross sectional diagram of an embodiment depicting thefirst interface of a back-up.

FIG. 16 is a cross sectional diagram of an embodiment depicting thefirst interface of a back-up.

FIG. 17 is another cross sectional diagram of an embodiment depictingthe first interface of a back-up.

FIG. 18 is another cross sectional diagram of an embodiment depictingthe first interface of a back-up.

FIG. 19 is another cross sectional diagram of an embodiment depictingthe first interface of a back-up.

FIG. 20 is another cross sectional diagram of an embodiment depictingthe first interface of a back-up.

FIG. 21 is another cross sectional diagram of an embodiment depictingthe first interface of a back-up.

FIG. 22 is a cross sectional diagram of an embodiment depicting thesecond interface of a back-up.

FIG. 23 is another cross sectional diagram of an embodiment depictingthe second interface of a back-up.

FIG. 24 is another cross sectional diagram of an embodiment depictingthe second interface of a back-up.

FIG. 25 is another cross sectional diagram of an embodiment depictingthe second interface of a back-up.

FIG. 26 is another cross sectional diagram of an embodiment depictingthe second interface of a back-up.

FIG. 27 is a cross sectional diagram of an embodiment depicting ananvil.

FIG. 28 is a cross sectional diagram of an embodiment depicting ananvil.

FIG. 29 is a top perspective diagram of an embodiment depicting ananvil.

FIG. 30 is a cross sectional diagram of an embodiment depicting thetapered portion of an anvil.

FIG. 31 is a cross sectional diagram of an embodiment depicting thecylindrical base of an anvil.

FIG. 32 is another cross sectional diagram of an embodiment depictingthe cylindrical base of an anvil.

FIG. 33 is another cross sectional diagram of an embodiment depictingthe cylindrical base of an anvil.

FIG. 34 is another cross sectional diagram of an embodiment depictingthe cylindrical base of an anvil.

FIG. 35 is another cross sectional diagram of an embodiment depictingthe cylindrical base of an anvil.

FIG. 36 is a cross sectional diagram of an embodiment depicting thecylindrical base of an anvil and the second interface of a back-up.

FIG. 37 is another cross sectional diagram of an embodiment depictingthe cylindrical base of an anvil and the second interface of a back-up.

FIG. 38 is another cross sectional diagram of an embodiment depictingthe cylindrical base of an anvil and the second interface of a back-up.

FIG. 39 is a cross sectional diagram of an embodiment depicting anelectrical insulator.

FIG. 40 is another cross sectional diagram of an embodiment depicting anelectrical insulator.

FIG. 41 is another cross sectional diagram of an embodiment depicting anelectrical insulator.

FIG. 42 is a cross sectional diagram of an embodiment depicting thecentering assembly.

FIG. 43 is another cross sectional diagram of an embodiment depictingthe centering assembly.

FIG. 44 is another cross sectional diagram of an embodiment depictingthe centering assembly.

FIG. 45 is a cross sectional diagram of an embodiment depicting thecooling chamber.

FIG. 46 is another cross sectional diagram of an embodiment depictingthe cooling chamber.

FIG. 47 is a cross sectional diagram of an embodiment of a back-up andanvil.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

FIG. 1 is a perspective diagram depicting an embodiment of a highpressure, high temperature press 100. In a preferred embodiment the highpressure, high temperature press 100 may comprise six cartridgeassemblies 101 that are connected to a press frame 102. The cartridgeassemblies 101 may converge within a central portion of the press frame102 to form a pressurized chamber that may be utilized to form superhard materials such as synthetic diamond or cubic boron nitride.

FIG. 2 is a perspective diagram depicting an embodiment of a pressurizedchamber 200 that may be formed when the distal ends 201 of the anvils202 attached to the cartridge assemblies 101 are adapted to convergewithin a central portion of the press frame 102. In a preferredembodiment the pressurized chamber 200 may comprise six anvils 202 thatform the polyhedron geometry of the pressurized chamber 200. In otherembodiments the pressurized chamber 200 may comprise at least fouranvils 202. The pressurized chamber 200 may be utilized to create andsustain an environment for a period of time that comprises highpressures and high temperatures that are especially conducive for theproduction of super hard material.

FIG. 3 is a perspective diagram of an embodiment of the currentinvention depicting the exterior portion of a cartridge assembly 101which may comprise a front end 300 and back end 301. The front end 300may be in communication with the back end 301, wherein the back end 301may comprise a means of housing hydraulic and electronic circuitry usedto produce the required pressures and temperatures for the production ofsuper hard material.

FIG. 4 is another perspective diagram of an embodiment of a cartridgeassembly 101 depicting a front end 300 which may comprise a key ring 400that further comprises at least one key slot 401 that may be adapted forreceiving at least one interfacing key 402 from an adjacent cartridgeassembly 101 when attached to the press frame. The at least one key slot401 and at least one interfacing key 402 may be disposed generallyaround a portion of the circumference of the key ring 400. In apreferred embodiment the key slots 401 and interfacing keys 402 mayserve to substantially hold the cartridge assemblies 101 in place duringoperation of the press 100 and help to prevent the cartridge assemblies101 from becoming misaligned and/or disconnected.

FIG. 5 is a top down perspective diagram of an embodiment of the currentinvention depicting a front end 300 that may comprise a centeringassembly 500 that may be encompassed by a key ring 400. In someembodiments the key ring 400 may comprise a plurality of receptacles 501for receiving a plurality of locking pins that may be adapted to centerthe centering assembly 500. Preferably there are at least 3 to 4 lockingpins. In other embodiments locking pins may also be adapted to centerthe anvil 202. In a preferred embodiment the centering assembly 500 maycomprise at least three receptacles 501 for receiving the locking pinsthat may also be adapted to center the centering assembly 500 within thekey ring 400. In some embodiments the ability to ensure that the anvils202 are substantially aligned within the pressurized chamber may assistto provide proper sealing between anvils and substantially reduce theprobability of shoulder loading and/or stress fractures.

FIG. 6 is a cross sectional diagram of the current invention depictingan embodiment of the front end 300 of a cartridge assembly 101comprising a back-up 600 intermediate and coaxial with an anvil 202 anda piston 601.

In a preferred embodiment the anvil 202 may comprise a proximal end 602in contact with the back-up 600 and a distal end 201 that may be adaptedto form part of a pressurized chamber 200 within the frame 102. Theanvil 202 may comprise a cylindrical base 603 connected to a taperedportion 604 leading to a working face 605 of the anvil opposite thebase. The tapered portion 604 may form a 35 to 55 degree angle with thecylindrical base 603 while the working face 605 may comprise a firstsurface area which is substantially parallel with the base. The anvil202 may also comprise a chamfered region 606 with a second surface areaforming a 0.5 to 3.5 degree angle with the tapered portion 604 and maybe connected to the working face 605 to form a frusto-pyramidal shape,wherein the second surface area may comprise a greater surface area thanthe first surface area. In some embodiments the second surface area ofthe anvil 202 may be adapted to receive any excess payload that mayextrude from the pressurized chamber 200 during a press cycle and may besubsequently utilized to form a natural gasket to prevent loss ofpressure. The unique geometry of the chamfered region 606 may alsoassist to reduce the effects of shoulder loading between anvils.

In another embodiment, the back-up 600 may comprise a truncated cylindercomprising a first interface 607 and second interface 608 that arejoined by a peripheral cylindrical wall 609. The back-up may comprise ahard material selected from the group consisting of refractory metals,carbides, tungsten carbides, niobium, titanium, platinum, molybdenum orcombinations thereof. The cylindrical wall 609 may comprise a portionextending normally from the periphery of the first interface 607 to aconcave portion 610 of the cylindrical wall 609. A layer of electricalinsulation 611 may be disposed around the periphery of the cylindricalwall 609 while an electrical insulated ring 612 may also be disposedaround the cylindrical wall 609, wherein the back-up 600 may besubstantially insulated from the piston 601. In some embodiments theability to effectively insulate the back-up 600 may be critical forachieving the proper charge through the anvil 202 to produce therequired temperature in the pressurized chamber 200. The concave portion610 of the back-up 600 may extend from the normal portion of thecylindrical wall 609 to the periphery of the second interface 608. Insome embodiments the concave portion 610 that may comprise a conicgeometry. Using the conic form factor where 0.5 is point to point and 1is point to intersect and v2/2 defining a round our concave conic formfactors may have a range from 0.6 to 0.9. The concave portion 610 of thebackup 600 may provide a means of effectively distributing load stressestowards the cylindrical base 603 of the anvil 202 which may reduce theamount of shoulder loading frequently experienced in similar presseswhich may cause stress fractures and subsequently cause the press tofail. Specifically, the concave portion 610 may enable the backup 600 toeffectively direct and concentrate stress lines from the first interface607 towards the second interface 608, such that the second interface 608comprises a significantly stress matched interface. In anotherembodiment a centering ring 613 may be disposed around the firstinterface 607 of the back-up 600 wherein at least a portion of acentering ring 613 may also be disposed within the concavity 614 of thepiston 601.

In yet another embodiment a hydraulic system (not shown) may be adaptedto apply axial pressure to the backup 600 through the piston 601 whereina central portion 615 of the piston 601 may comprise an axial thicknessapproximately equal to the axial length of the backup 600. The proximalend 616 of the back-up 600 may fit within a recess 617 formed in thepiston 601 wherein the recess 617 may comprise a cylindrical side wall618 and a bottom floor 619. In some embodiments a corner 620 between thebottom floor 619 and the side wall 618 may comprise a conic form factorof 0.6 to 0.9 and the sidewall 618 may also be in contact with the keyring 400. In other embodiments the corner 620 between the bottom floor619 and the side wall 618 may comprise a conic form factor of 0.6 to0.9. and the corner 620 may form a concavity 614 in the bottom floor619. The concavity 614 may comprise a depth of approximately 10 to 33percent of the axial length of the side wall 618, the depth beingapproximately twice the width of the concavity 614. The piston 601 mayfurther comprise an open cavity 621 formed in the opposite end,proximate the back-up 600 wherein the cavity 621 may comprise a depth ofabout 50 to 90 percent of the depth of the axial thickness of thecentral portion 615 of the piston 601 and a width of about 75 to 125percent the depth. In some embodiments the axial thickness of thecentral portion 615 of the piston 601 may be 40 to 80 percent the radialthickness of the piston 601. In a preferred embodiment the piston 601may comprise a geometry such that when the hydraulic system appliesaxial pressure through the piston 601, the end of the piston 601distributes the load substantially evenly across a cross sectional areaof the proximal end 616 of the back-up 600. In yet other embodiments theproximal end of the back-up 600 may comprise a geometry such that whenthe hydraulic system applies the axial pressure through the piston 601,the piston 601 may distribute the load substantially evenly across across sectional area of the proximal end 616 of the back-up 600.

FIGS. 7-12 are cross sectional diagrams of embodiments of variousgeometries of the recess portion 617 of a piston 601. In a preferredembodiment the recess portion 617 may comprise a generally flat geometryas shown in FIG. 7. In other embodiments the recess portion 617 maycomprise a generally inverted triangular shape as shown in FIG. 8, agenerally domed shape as shown in FIG. 9, a generally scoop shape asshown in FIG. 10, a generally frustoconical shape as shown in FIG. 11,an inverted chamfer as shown in FIG. 12, or combinations thereof. Thevarious geometries may further assist to substantially distribute stressloads across the recess portion 617 of the piston 601 in an effort toreduce shoulder loading or stress fractures and to provide asubstantially stress matched interface.

FIGS. 13-14 are cross sectional diagrams depicting the comparisonsbetween stress loads affecting the back-up 1300 of prior art and theback-up 600 of the current invention. FIG. 13 specifically depicts howstress loads may be displaced in a back-up 1300 of prior art which maybe directed towards the corner portions 1301 of the second interface608. This may cause the second interface 609 to bend which may break theback-up. FIG. 14 depicts how a back-up 600 of the current inventioncomprising a concave portion 610 with a conic geometry may effectivelydirect load stresses substantially evenly across the interfaces 608,609. Substantially even loading will mitigate bending and preserve thelife of the back-up.

FIGS. 15-20 are cross sectional diagrams of embodiments of variousgeometries of the first interface 608 of a back-up 600. In a preferredembodiment the first interface 608 may comprise a generally flat shapeas shown in FIG. 15. In other embodiments the first interface 608 maycomprise a generally triangular shape as shown in FIG. 16, a generallyscoop shape as shown in FIG. 17, a generally frustoconical shape asshown in FIG. 18, a generally dome shape as shown in FIG. 19, a chamferas shown in FIG. 20, or combinations thereof. The various geometries mayfurther assist to substantially redistribute stress loads across thefirst interface 608 of the back-up 600 in an effort to reduce shoulderloading or stress fractures and to provide a substantially stressmatched interface.

FIGS. 21-26 are cross sectional diagrams of embodiments of variousgeometries of the second interface 609 of a back-up 600. In a preferredembodiment the second interface 609 may comprise a generally flat shapeas shown in FIG. 21. In other embodiments the second interface 609 maycomprise a generally triangular shape as shown in FIG. 22, a generallydomed shape as shown in FIG. 23, a generally scoop shape as shown inFIG. 24, a generally frustoconical shape as shown in FIG. 25, aninverted chamfer as shown in FIG. 26, or combinations thereof. Thevarious geometries may further assist to substantially redistributestress loads across the second interface 609 of the back-up 600 in aneffort to reduce shoulder loading or stress fractures and to provide asubstantially stress matched interface. In a preferred embodiment thesecond interface 609 may comprise a generally a geometry thatcorresponds to the geometry of the cylindrical base 603 of the anvil202.

FIG. 27 is a perspective diagram of an embodiment of the currentinvention depicting an anvil 202 which may comprise a material selectedfrom the following consisting a cemented metal carbide, tungstencarbide, or combinations thereof. The anvil 202 may comprise acylindrical base 603 connected to a tapered portion 604 leading to aworking face 605 of the anvil 202 opposite the base. In some embodimentsthe tapered portion 604 may form a 45 degree angle with the cylindricalbase 603 while the chamfered region 606 may comprise a second surfacearea that substantially forms a 2.5 degree angle 2700 with the taperedportion 604. In other embodiments the anvil 202 may comprise a generallyfrusto-pyramidal shape comprising rounded corners further comprising aconic form factor of 0.6 to 0.9. In some embodiments the anvil 202 maycomprise a distal end 201 which is adapted to form a part of apressurized chamber within the press frame.

FIG. 28 is a top perspective diagram of an embodiment depicting an anvil202. The anvil 202 may comprise a chamfered region 606 that comprises asecond surface area that is 1.1 to 2.5 times greater than the firstsurface area of the working face. In a preferred embodiment the secondsurface area may comprise a surface area 1.5 times greater than thefirst surface area. In other embodiments the anvil 202 may comprise achamfered region 606 that forms a wedge area for receiving excesspayload that may extrude from the pressurized chamber 200 and form agasket when the anvils 202 are brought together within the press 100during operation.

FIG. 29 is a cross sectional diagram of an embodiment of the currentinvention depicting an anvil 202 that may comprise a cylindrical base603 comprising a flat geometry and a tapered portion 604 that maycomprise a conic geometry 3000. The conic geometry may assist the anvil202 to redirect stress loading towards the pressurized chamber andassist to reduce the probability of shoulder loading.

FIGS. 30-34 are cross sectional diagrams of various embodiments of ananvil 202 depicting various geometries of the cylindrical base 603 thatmay comprise a generally triangular shape, a generally dome shape, agenerally scoop shape, a frustoconical shape, a chamfer. FIG. 30 depictsa cylindrical base 603 comprising a generally triangular shape. FIG. 31depicts a cylindrical base 603 comprising a domed shape while FIG. 32depicts a generally scoop shape. FIG. 33 depicts a generallyfrustoconical shaped cylindrical base 603 while FIG. 34 depicts achamfered shape. In some embodiments the various geometries of thecylindrical base 603 may serve to compliment and further enhance thegeometry of the back-up to effectively direct the stress loads towardsthe pressurized chamber of the press.

FIGS. 35-37 are cross sectional diagrams of various embodiments of ananvil 202 depicting a cylindrical base 603 comprising various diametersthat may be mated with the first interface 608 of a back-up 600. FIG. 35depicts a cylindrical base 603 that may comprise a diameter that issubstantially equal to the second interface 609 of the backup 600. Theembodiment also depicts a chamfered region 606 that may comprise asecond surface area that further comprises a conic geometry. In yetother embodiments the second surface area may also comprise a radius.FIG. 36 depicts a cylindrical base 603 that may comprise a diameter thatis larger than the diameter of a second interface 609 of the back-up600. In another embodiment the cylindrical base 603 may comprise adiameter that is smaller than the diameter of second interface 609 ofthe back-up as shown in FIG. 37.

FIGS. 38-40 are perspective diagrams of various embodiments of thecurrent invention depicting an electrical insulation 3800 that may bedisposed proximate the first interface 608 of the back-up and piston601. The insulation may comprise a generally circular geometry havingvarious laser cut sectionals disposed around the circumference of theinsulation. The electrical insulation 3800 may be selected from thefollowing material consisting of glass epoxy resin laminate, Kevlar,Teflon, compressed inorganic powder or combinations thereof. Theelectrical insulation 3800 may comprise a thickness of between 0.032 and0.5 inches. Referring now to FIG. 38 which may comprise an electricalinsulation 3800 comprising straight laser cut sectionals 3801, FIG. 39may comprise an electrical insulation 3800 comprising generally curvedsectionals 3900 while FIG. 40 may comprise an electrical insulation 3800comprising generally jagged sectionals 4000. The sectionals may providea certain degree of allowance and assist to prevent the insulation fromshattering when subjected to intense pressure between the back-up 600and the piston 601.

FIGS. 41-44 are cross sectional diagrams of various embodiments of thecurrent invention depicting a centering assembly 500 that may alsocomprise a plurality of springs in contact with the back-up 600. In someembodiments the plurality of springs may assist to prevent the centeringassembly 500 from being forced up into the pressurized chamber of thepress by providing a small degree of allowance in the event that theback-up 600 begins to expand during operation. The spring assembly asshown in FIG. 41 may comprise a plurality of finger springs 4100, aplurality of compression springs 4200 in FIG. 42, a plurality of volutesprings 4300 in FIG. 43 or a plurality leaf springs 4400 as in FIG. 44disposed around the circumference of the back-up 600.

FIGS. 45-46 are cross sectional diagrams of various embodiments of thecurrent invention depicting a centering assembly 500 that may bedisposed intermediate a key ring (not shown) and an anvil 202. Thecentering assembly 500 may comprise a cooling mechanism 4500 whichcomprises a chamber 4501 which may be adapted for flowing cooling fluidthrough. The cooling mechanism 4500 may assist to substantially cool theanvil 202 especially when subjected to such extremely high temperaturesduring operation. FIG. 45 depicts an embodiment of a chamber 4501 thatmay comprise an opening which exposes the cooling fluid directly to theanvil 202. In some embodiments this may assist to provide immediatecooling to the anvil and help to drastically lower the temperature ofthe anvil during operation. FIG. 46 however, depicts another embodimentwherein the cooling fluid is isolated from the anvil. In someembodiments this may help to prevent the chamber 4501 from beingaffected in the event that the anvil experiences some distortion duringformation of the super hard material.

FIG. 47 is a cross sectional diagram of an embodiment of a back-up 600and anvil 202. The distal end of the back-up comprises a non-planargeometry, while the proximal end of the back-up comprises a planargeometry. It is believed that such an arrangement may more evenlydistribute the stress from the back-up to the anvil then if both endswere planar and avoid the stress concentrating at the periphery.

Whereas the present invention has been described in particular relationto the drawings attached hereto, it should be understood that other andfurther modifications apart from those shown or suggested herein, may bemade within the scope and spirit of the present invention.

1. A cartridge assembly adapted for connection to a frame of a highpressure, high temperature press, comprising: a front end comprising aback up intermediate and coaxial with an anvil and a piston; thecartridge assembly comprising a hydraulic system adapted to apply axialpressure to the back-up through the piston; a central portion of thepiston comprising a axial thickness approximately equal to the axiallength of the back-up.
 2. The cartridge assembly of claim 1, wherein aproximal end of the back-up fits within a recess formed in the piston.3. The cartridge assembly of claim 2, wherein the recess comprises acylindrical side wall and a bottom floor.
 4. The cartridge assembly ofclaim 3, wherein a corner of the wall and floor form a concavity.
 5. Thecartridge assembly of claim 3, wherein the corner between the concavityform a radius.
 6. The cartridge assembly of claim 3, wherein theconcavity comprises a conic form factor of 0.6 to 0.9.
 7. The cartridgeassembly of claim 6, wherein at least a portion of a centering ringsurrounding the back-up is disposed within the concavity.
 8. Thecartridge assembly of claim 6, wherein concavity comprise a depth ofapproximately 10 to 33 percent of the axial length of the side wall. 9.The cartridge assembly of claim 6, wherein the concavity comprise adepth and a width, wherein the depth is approximately twice the width.10. The cartridge assembly of claim 3, wherein the side wall contacts akey ring adapted to interlock with adjacent cartridges when attached tothe high pressure high temperature frame.
 11. The cartridge assembly ofclaim 10, wherein the key ring comprises a plurality of slots adapted toreceive locking pins adapted to center anvil.
 12. The cartridge assemblyof claim 11, wherein a centering assembly is disposed intermediate thekey ring and the anvil.
 13. The cartridge assembly of claim 12, whereinthe centering assembly comprises a mechanism for cooling the anvil. 14.The cartridge assembly of claim 1, wherein the back-up is electricallyinsulated from the piston.
 15. The cartridge assembly of claim 1,wherein a central open cavity is formed in the piston opposite an endproximate the back-up.
 16. The cartridge assembly of claim 15, whereinthe open cavity comprises a depth of about 50 to 90 percent of the axialthickness of the central portion of the piston.
 17. The cartridgeassembly of claim 16, wherein the open cavity comprises a width of about75 to 125 percent of the depth of the open cavity.
 18. The cartridgeassembly of claim 1, wherein the axial thickness of the central portionof the piston is 40 to 80 percent of a radial thickness of the piston.19. The cartridge assembly of claim 1, wherein a proximal end of theback-up comprises a geometry such that when the hydraulic system appliesthe axial pressure through the piston, that the piston distributes theload substantially evenly across a cross sectional area of the proximalend of the back-up.
 20. The cartridge assembly of claim 1, wherein anend of the piston comprises a geometry such that when the hydraulicsystem applies the axial pressure through the piston, that the end ofthe piston distributes the load substantially evenly across a crosssectional area of the proximal end of the back-up.